• Journal of the Optical Society of Korea
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• 제16권4호
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• pp.349-353
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• 2012

Uniform spreading of injection current in light-emitting diodes (LEDs) is one of the crucial requirements for better device performances. It is reported that non-uniform current spreading leads to low output power, high current crowding, heating, and reliability degradation of the LED device. This paper reports on the effects of different surface and electrode geometries in the LEDs. To increase the output power of LEDs and reduce the series resistance, a rectangular-type LED (RT-LED) with a centered island cathode has been fabricated and investigated by comparison with a conventional LED (CV-LED). The performances of RT-LEDs were prominently enhanced via uniform current spreading and low current crowding. Performances in terms of increased output power and lower forward voltage of simulated RT-LEDs are much superior to those of CV-LEDs. Based on these results, we investigated the correlation between device geometries and optical characteristics through the fabricated CV and RT-LEDs. The measured output power and forward voltage of the RT-LEDs at 100 mA are 64.7% higher and 8% smaller compared with those of the CV-LEDs.

• 대한소아치과학회지
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• 제46권1호
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• pp.57-63
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• 2019

이 연구의 목적은 고출력 발광 다이오드 광중합기의 Xtra Power 및 High Power mode의 짧은 중합시간이 레진 치면열구전색제의 중합에 충분한지를 확인하는 것이다. 금속 주형을 이용해 시편을 제작하여 미세경도를 측정하였으며, 기존의 발광 다이오드 광중합기로 중합한 시편의 미세경도와 비교하였다. 그 결과, High Power mode로 8초, Xtra Power mode로 3초 중합한 filled sealant와 High Power mode로 8초, 12초, Xtra Power mode로 6초 중합한 unfilled sealant의 상면과 하면 모두에서 대조군보다 유의하게 낮은 미세경도를 나타냈다(p = 0.000). 이 연구를 통하여 중합 시간과 전색제의 종류를 고려한 특정 조건에서 고출력 발광 다이오드 광중합기의 Xtra Power 및 High Power mode의 짧은 중합시간이 치면열구전색제를 적절히 중합하기에 충분하지 않음을 알 수 있었다.

• 한국재료학회지
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• 제23권3호
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• pp.177-182
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• 2013

Nanosphere lithography is an inexpensive, simple, high-throughput nanofabrication process. NSL can be done in different ways, such as drop coating, spin coating or by means of tilted evaporation. Nitride-based light-emitting diodes (LEDs) are applied in different places, such as liquid crystal displays and traffic signals. The characteristics of gallium nitride (GaN)-based LEDs can be enhanced by fabricating nanopatterns on the top surface of the LEDs. In this work, we created differently sized (420, 320 and 140 nm) nanopatterns on the upper surfaces of GaN-based LEDs using a modified nanosphere lithography technique. This technique is quite different from conventional NSL. The characterization of the patterned GaN-based LEDs revealed a dependence on the size of the holes in the pattern created on the LED surface. The depths of the patterns were 80 nm as confirmed by AFM. Both the photoluminescence and electroluminescence intensities of the patterned LEDs were found to increase with an increase in the size of holes in the pattern. The light output power of the 420-nm hole-patterned LED was 1.16 times higher than that of a conventional LED. Moreover, the current-voltage characteristics were improved with the fabrication of differently sized patterns over the LED surface using the proposed nanosphere lithography method.

• 한국전기전자재료학회논문지
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• 제20권12호
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• pp.1087-1092
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• 2007

We developed the 4-channel Light Medical Therapy Apparatus for Skin Injury Cure using a high brightness LED. This equipment was fabricated using a micro-controller and a high brightness LED, and designed to enable us to control light irradiation time, intensity and reservation. In this paper, the designed device was used to find out how high brightness LED light affects the skin injury of SD-Rat(Sprague-Dawley Rat). In the experiment, $1\;cm^2$ wounds on the skin injury of SD-Rat(Sprague-Dawley Rat) were made. Light irradiation group and none light irradiation group divided, each group was irradiated one hour a day for 14 days. In result, compared with none light irradiation group, the lower incidence of inflammation and faster recovery was shown in light irradiation group.

• 한국산학기술학회논문지
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• 제10권7호
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• pp.1514-1519
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• 2009

400nm 파장을 방출하는 GaN LED를 제조하여, n-GaN층과 p-GaN층의 위에 있는 ITO층 표면에 패턴을 만들어 광 추출 효율을 향상시켰다. 추가적으로, n과 p패드 아래와 칩의 바닥면에 각각 광반사 금속을 설치하였다. 광 추출 효율은 20mA에서 n-GaN의 텍스쳐링에 의해 20% 증가되었고 ITO의 텍스쳐링에 의해 18% 증가되었다. 표면 처리가 않된 LED와 비교해서 n-GaN와 ITO를 함께 표면 텍스쳐링 했을때의 광 추출 효율은 20mA에서 32% 증가되었다.

• 조명전기설비학회논문지
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• 제25권10호
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• pp.14-22
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• 2011

The artificial lights to be introduced for the plant factories is requiring the artificial light resources with minimizing the energy consumption to reduce the greenhouse gases which is a major cause of global warming, and maximizing the efficiency in photosynthesis effect light-wave range, in which the plants can be greatly grown and developed, and having the signal light-wave range for forming the light types. the best growing and developing environment for the plants has recently realized with utilizing the LED(Lighting Emitting Diode) lamps, as a environment-friendly green lamps, which can elevating the light efficiency with using only the specific light wave range. In this study, to provide the necessary lights for the full artificial light type of the plant factory, the following research/study and experiments has been conducting. experiments of the spectrum for each light sources, and LED, The intensity of illumination, Irradiance, Photosynthesis Photon Flux Density.

• 한국생산제조학회지
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• 제20권3호
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• pp.361-367
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• 2011

In this paper, it was attempted to analyze the optimal design of light emitting diode (LED), a source of back light unit (BLU). LED is beginning with commercialized red LED which is made by GaAsP compound semiconductor, and has been developed focusing on liquid crystal panel. In order to get the optimal design, optical simulation was made by analyzing luminosity shape, reflector angle, chip depth, and chip position of LED lighting. Final results show that the proposed LED characteristics were useful to increase light efficiency and it has been proven by distribution chart for actual exposed light on the light guide panel (LGP).

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.222-223
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• 2011

최근 저전력 소모와 얇은 두께, 무 수은, 다양한 색 표현력, 빠른 응답 속도 등의 다양한 장점을 가진 LED(Light Emitting Diode)를 광원으로 이용하는 LCD(Liquid Crystal Display) TV가 큰 주목을 받고 있다. 이러한 LCD TV의 화면을 균등한 휘도로 표현하기 위해 기존의 구동회로는 다 채널의 LED를 정전류로 제어하는 DC/DC 컨버터가 채널마다 각각 적용되었고, 이는 원가 상승 및 효율 저하의 원인이 되었다. 이를 해결하기 위하여 본 논문에서는 각 LED 채널에 적용되는 DC/DC 컨버터 없이 트랜스포머, 커패시터, 다이오드를 이용하여 모든 LED 채널의 정전류 제어가 가능한 저가격형 구동회로를 제안한다. 이는 전력변환 효율과 전력밀도를 획기적으로 개선할 수 있고 수동소자만을 사용하므로 높은 신뢰성을 확보할 수 있다. 본 논문에서는 제안된 회로에 대한 이론적 해석과 실험을 통해 제안 회로의 타당성을 검증한다.

• 정보와 통신
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• 제28권12호
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• pp.50-60
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• 2011

Visible light communication(VLC) is one type of short-range, optical, and wireless communication system utilizing light emitting diode(LED) and laser diode(LD) as optical source. In a VLC system, visible light is used as a transmission medium and used to illuminate. Using VLC has a lot of advantages: it is harmless to human body; it transmits with high power, and it has excellent security, a high data rate, and a license free frequency band. With such a unique blend of communication and illumination in one system, the most common application would be an indoor environment. We aim at reviewing key issues in VLC network such as : FOV(field of view), priority MAC, cooperative MAC, link switching, LED-ID technique, cell site diversity, and link recovery.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.126-129
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• 2001

A p-n junction was obtained by the deposition of an n-type ZnO thin film on a p-type Zn-doped InP substrate. The Zn-doped InP substrate has been made by the diffusion of Zn with sealed ampoule technique. The ZnO deposition process ws performed by pulsed laser deposition (PLD). The p-n junction was formed and showed a typical I-V characteristic. We will also discuss about the realization of an ultraviolet light-emitting diode (LED). The structure of n-ZnO/p-Zn-doped InP could be a good candidate for the realization of an ultraviolet light-emitting diode or an ultraviolet laser diode.